Aldiko and Kindle? They're okay. I don't have problems with them, but I consider myself relatively technologically skilled, so I don't know if that would be the case of others. For what it's worth, I think that both are considered good apps.

Screen quality is often ignored when talking about tablets and ereaders. Many only look at the resolution... If that. But these devices are mostly screens, so I think people should be careful about the screen quality, and I make a point of bringing up the point when talking about the different devices.